139 lines
2.5 KiB
C
139 lines
2.5 KiB
C
#include <libopencm3/stm32/usart.h>
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#include <libopencm3/stm32/gpio.h>
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#include <libopencm3/cm3/nvic.h>
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#include "pinout.h"
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#include "rs485.h"
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#define RS485_BUFFER_SIZE 128
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static volatile char debugBuffer[RS485_BUFFER_SIZE];
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static volatile uint16_t readPos, writePos;
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static volatile uint8_t bufferFull, bufferEmpty, usartActive;
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void rs485_init(void)
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{
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// initialize the ring buffer
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readPos = 0;
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writePos = 0;
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bufferFull = 0;
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bufferEmpty = 1;
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usartActive = 0;
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/* Initialize GPIOs */
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// RS485 drive enable signal
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gpio_clear(RS485_PORT, RS485_DE_PIN);
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gpio_mode_setup(RS485_PORT, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, RS485_DE_PIN);
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// RX and TX pins
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gpio_mode_setup(RS485_PORT, GPIO_MODE_AF, GPIO_PUPD_NONE, RS485_TX_PIN | RS485_RX_PIN);
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gpio_set_af(RS485_PORT, GPIO_AF0, RS485_TX_PIN | RS485_RX_PIN);
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// enable interrupt
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nvic_enable_irq(NVIC_USART1_IRQ);
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/* Setup USART1 parameters. */
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usart_set_baudrate(USART1, 115200);
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usart_set_databits(USART1, 8);
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usart_set_stopbits(USART1, USART_CR2_STOPBITS_1);
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usart_set_mode(USART1, USART_MODE_TX);
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usart_set_parity(USART1, USART_PARITY_NONE);
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usart_set_flow_control(USART1, USART_FLOWCONTROL_NONE);
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/* Enable the USART. */
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usart_enable(USART1);
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/* Enable the USART1 TX Interrupt */
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usart_enable_tx_interrupt(USART1);
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usart_enable_tx_complete_interrupt(USART1);
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}
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static void rs485_transfer(void)
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{
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if(bufferEmpty) {
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usart_disable_tx_interrupt(USART1);
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usartActive = 0;
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return;
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}
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usart_send(USART1, debugBuffer[readPos]);
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readPos++;
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if(readPos == RS485_BUFFER_SIZE) {
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readPos = 0;
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}
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if(readPos == writePos) {
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bufferEmpty = 1;
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}
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bufferFull = 0;
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usart_enable_tx_interrupt(USART1);
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}
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void usart1_isr(void)
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{
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if(USART1_ISR & USART_ISR_TXE) {
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rs485_transfer();
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}
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if(USART1_ISR & USART_ISR_TC) {
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USART1_ICR |= USART_ICR_TCCF;
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if(!usartActive) {
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gpio_clear(RS485_PORT, RS485_DE_PIN);
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}
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}
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}
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void rs485_enqueue(const char *str)
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{
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while(*str) {
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if(bufferFull) {
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break;
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}
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debugBuffer[writePos] = *str;
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writePos++;
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if(writePos == RS485_BUFFER_SIZE) {
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writePos = 0;
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}
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if(writePos == readPos) {
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bufferFull = 1;
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}
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bufferEmpty = 0;
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str++;
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}
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if(!usartActive) {
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usartActive = 1;
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gpio_set(RS485_PORT, RS485_DE_PIN);
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rs485_transfer();
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}
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}
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void rs485_deepsleep_prepare(void)
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{
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// force the transceiver to RX mode
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gpio_clear(RS485_PORT, RS485_DE_PIN);
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}
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void rs485_deepsleep_resume(void)
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{
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// if a transmission is still in progress, switch to TX mode again
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if(usartActive) {
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gpio_set(RS485_PORT, RS485_DE_PIN);
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}
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}
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